Items of metal based jewelry (i.e., entirely or partially made of precious metal or with base metal closure elements) of the encircling type, e.g., most commonly watches and bracelets around the wrist, necklaces around the neck and anklets around the ankle, are often made in openable form for ease of placement on the limb or body part being adorned (bangles and continuous necklaces are large enough to be directly placed as unitary pieces and are accordingly not included in this discussion or the present invention).
In order to maintain the items of openable jewelry in place, metal items are provided with primary latching devices such as the common compressible "tongue in groove" wherein a compressible triangulated tongue on one end of the item to be closed is fitted into a corresponding receiving groove in the other end. The tongue is compressed until fully seated and springs open to engage a catch member or edge of the insertion aperture to prevent disengagement unless the tongue is again compressed by a release button or control. Other similar latching mechanisms abound and often the particular type of catch is determined by the aesthetics of the piece. Examples of other latching devices include spring-like beveled insertion members which are moved to an insertion position which resists opening. The control release in such embodiments operates movement of the bevel member to release the resistance.
One of the considerations for the primary latches is that they be substantially or completely hidden during use (except, necessarily for the release control) whereby they do not interfere with the aesthetics of the piece. This is especially important since the primary latches are normally large in size and span a substantial portion of the interface between the abutted ends.
Because of the value of jewelry and the fact that on a person's body it often may come into contact with other objects (clothing, walls, furniture, other people, etc.), with the release button or control being inadvertently activated, such jewelry (with some exceptions for aesthetic reasons) is usually also provided with a secondary safety catch. The secondary safety catch prevents the accidental loss of an expensive jewelry item should the primary catch fail or accidentally open. Often, however, since it is only secondary in nature, the mechanism of the secondary catch is very rudimentary and is prone to a high degree of failure. The most common secondary catch is a small hinged metal loop on one open end of the bracelet, watch and the like, with the other open end being provided with a post adapted to be frictionally engaged with the loop. The loop and post are usually positioned on a side or side edge of the bracelet, watch and the like whereby they are less conspicuous with respect to the aesthetics of the jewelry item. Release is effected by a hinged flipping back of the loop from engagement with the post.
A problem with the common secondary safety latches, which are operable by frictional engagement, is that over time and under pressure, the metal of the loop and/or the post tend to deform ever so slightly (and generally imperceptibly) but sufficiently such that the frictional engagement is tenuous at best and flipping off of the loop from the post can be effected by a simple touch or gravity. As a result, the safety function is compromised or lost, and very often without the wearer even being aware of such condition. However, providing a secondary safety latch of a substantive nature, akin to that of the primary latch (which is less subject to deterioration) is normally not physically or aesthetically feasible with unaesthetic bulk and unnecessarily complicated procedures in removal or placement of the jewelry item.